Module Name: src
Committed By: riastradh
Date: Tue Aug 20 12:33:05 UTC 2019
Modified Files:
src/sys/arch/amd64/include: param.h
src/sys/arch/i386/include: param.h
src/sys/sys: param.h
Log Message:
New macro ALIGNED_POINTER_LOAD.
To be used with ALIGNED_POINTER(p,t) instead of writing *(const t *)p
directly. This way, on machines without strict alignment, we can use
memcpy to pacify sanitizers, while getting the same compiled code in
the end with a single (say) MOV instruction.
To generate a diff of this commit:
cvs rdiff -u -r1.30 -r1.31 src/sys/arch/amd64/include/param.h
cvs rdiff -u -r1.84 -r1.85 src/sys/arch/i386/include/param.h
cvs rdiff -u -r1.609 -r1.610 src/sys/sys/param.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/amd64/include/param.h
diff -u src/sys/arch/amd64/include/param.h:1.30 src/sys/arch/amd64/include/param.h:1.31
--- src/sys/arch/amd64/include/param.h:1.30 Sat Mar 16 11:50:48 2019
+++ src/sys/arch/amd64/include/param.h Tue Aug 20 12:33:04 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: param.h,v 1.30 2019/03/16 11:50:48 rin Exp $ */
+/* $NetBSD: param.h,v 1.31 2019/08/20 12:33:04 riastradh Exp $ */
#ifdef __x86_64__
@@ -21,7 +21,8 @@
#define MACHINE_ARCH "x86_64"
#define MID_MACHINE MID_X86_64
-#define ALIGNED_POINTER(p,t) 1
+#define ALIGNED_POINTER(p,t) 1
+#define ALIGNED_POINTER_LOAD(q,p,t) memcpy((q), (p), sizeof(t))
/*
* Align stack as required by AMD64 System V ABI. This is because
Index: src/sys/arch/i386/include/param.h
diff -u src/sys/arch/i386/include/param.h:1.84 src/sys/arch/i386/include/param.h:1.85
--- src/sys/arch/i386/include/param.h:1.84 Mon Jan 7 22:00:31 2019
+++ src/sys/arch/i386/include/param.h Tue Aug 20 12:33:04 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: param.h,v 1.84 2019/01/07 22:00:31 jdolecek Exp $ */
+/* $NetBSD: param.h,v 1.85 2019/08/20 12:33:04 riastradh Exp $ */
/*-
* Copyright (c) 1990 The Regents of the University of California.
@@ -58,7 +58,8 @@
#define MACHINE_ARCH "i386"
#define MID_MACHINE MID_I386
-#define ALIGNED_POINTER(p,t) 1
+#define ALIGNED_POINTER(p,t) 1
+#define ALIGNED_POINTER_LOAD(q,p,t) memcpy((q), (p), sizeof(t))
#define PGSHIFT 12 /* LOG2(NBPG) */
#define NBPG (1 << PGSHIFT) /* bytes/page */
Index: src/sys/sys/param.h
diff -u src/sys/sys/param.h:1.609 src/sys/sys/param.h:1.610
--- src/sys/sys/param.h:1.609 Tue Aug 20 06:37:06 2019
+++ src/sys/sys/param.h Tue Aug 20 12:33:04 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: param.h,v 1.609 2019/08/20 06:37:06 mrg Exp $ */
+/* $NetBSD: param.h,v 1.610 2019/08/20 12:33:04 riastradh Exp $ */
/*-
* Copyright (c) 1982, 1986, 1989, 1993
@@ -253,9 +253,22 @@
* any desired pointer type.
*
* ALIGNED_POINTER is a boolean macro that checks whether an address
- * is valid to fetch data elements of type t from on this architecture.
- * This does not reflect the optimal alignment, just the possibility
- * (within reasonable limits).
+ * is valid to fetch data elements of type t from on this architecture
+ * using ALIGNED_POINTER_LOAD. This does not reflect the optimal
+ * alignment, just the possibility (within reasonable limits).
+ *
+ * uint32_t x;
+ * unsigned char *p = ...;
+ *
+ * if (ALIGNED_POINTER(p, uint32_t)) {
+ * uint32_t t;
+ * ALIGNED_POINTER_LOAD(&t, p, uint32_t);
+ * x = t;
+ * } else {
+ * uint32_t t;
+ * memcpy(&t, p, sizeof(t));
+ * x = t;
+ * }
*
*/
#define ALIGNBYTES __ALIGNBYTES
@@ -265,6 +278,9 @@
#ifndef ALIGNED_POINTER
#define ALIGNED_POINTER(p,t) ((((uintptr_t)(p)) & (sizeof(t) - 1)) == 0)
#endif
+#ifndef ALIGNED_POINTER_LOAD
+#define ALIGNED_POINTER_LOAD(q,p,t) (*(q) = *((const t *)(p)))
+#endif
/*
* Historic priority levels. These are meaningless and remain only
